People with movement disabilities because of spinal cord injury, brain injury or other impairments of the motor system are greatly affected in their everyday life, in many cases to the extent that everyday life is impossible without continuous help. In Denmark there are more than 30,000 wheelchair users, and in the U.S. there are 200,000 people with spinal cord injuries. Any increase of self-supportiveness, maybe even to the ability of possessing a job, is crucial to improve the quality of life for these disabled individuals.
With the modern Internet and communication technology, jobs, sociability and even health care is no longer linked to the physical presence of the persons involved, but the internet has become a virtual world in which only the computer access limits the individual contribution. Here severely paralysed persons, who have lost even the ability to speak and for whom the only way of real communication is through a computer, could even possess jobs, and thereby highly improve their quality of life, as long as they have an efficient computer control. With the increased computerisation of everyday equipment, such as automatic doors, kitchen hardware, telephones, TVs, several everyday tasks can be automated. While this automation is convenient for most of us, it is potentially invaluable for increasing independence and quality of life for disabled persons. An effective control method to access these things can significantly improve the quality of life for millions of disabled all over the world.
Currently, the most successful control methods within communication are eye control devices (Gips J, DiMattia P, Curran F X and Olivieri P, “Using EagleEyes—an Electrodes Based Device for Controlling the Computer with Your Eyes”, in “Interdisciplinary Aspects on Computers Helping People with Special needs” J. Klaus, e. Auff, W. Kremser, W. Zagler (eds.). R Oldenbourg, Vienna, 1996, LC Technologies, Inc. Eyegaze Systems Eyetracking 9455 Silver King Court Fairfax, Va. 22031), head control devices, voice recognition and the tongue control device (Patent: WO9307726, New Abilities Systems Inc., 1993). Still there are a number of problems related to the effectiveness of the use of these methods. The use of the eye for control demands high concentration and often results in headaches, one. explanation of the problems with this method is the fact that the eye is a sensor or an input device, and that makes it difficult for the brain to learn the control in which the eye is an output device. Problems are also related to determining whether a point of interest is found by the user or the user is simply gazing, the latter leading to false detections. Voice recognition is quite a fast way to effectuate a command, but may be sensitive to interference. Further, it is limited to be used by the disabled with intact language, and it has not been developed for all languages. The head control systems often demands high concentration and the requirement of exact control of the head movements often results in neck pain.
The tongue control methods are favourable since they are practically invisible and manageable for people with even severe disabilities. A comparative study, comparing a tongue control method to a head control system and a rather simple mouth stick, resulted in all four quadriplegic test persons preferring the tongue based control system, even though it was not the fastest system (C. Lau and S. O'Leary, “Comparison of Computer Interface Devices for Persons with Severe Physical Disabilities”, The American Journal of Occupational Therapy, vol. 47, pp. 1022-1030, 1993). Current tongue control systems are mainly based on pressure sensitive buttons placed in the mouth cavity over the tongue (Patent: WO9307726, New Abilities Systems Inc., 1993). The use of pressure sensitive sensors does not seem optimal, since normal speech and swallowing generates tongue-palatal pressures in the range of 20-60% of maximal achievable pressure (Müller, E, at al. “Perioral tissue mechanics during speech production”. In J. Eisenfeld & C. DeLisi (Eds.) “Mathematics and computers in biomedical application” Elsevier Science publishers B.V., 1984″, Hayashi R, Tsuga K, Hosokawa R, et al., “A novel handy probe for tongue pressure measurement” International Journal Of Prosthodontics 15(4): 385-388 JULY-AUGUST 2002), which poses demands on the detection threshold and therefore may increase the risk of fatigue. Further the use of pressure-based sensors strongly limits the maximal number of sensors that can be placed in the oral cavity since the pressure increase the tongue-palatal contact area. Having only 9 control buttons the commercially available tongue touch keypad from New Abilities Systems (Patent: WO9307726, New Abilities Systems Inc., 1993) far from utilizes the high selectivity in the movement of the tongue, which readily can pick out every single of our 32 teeth. This selectivity is in theory sufficient to select the alphabet directly on 26 buttons, although a different sensor type will have to be developed. Such a direct letter selection would bring the typing ability of a quadriplegic on the level of an intact person using one finger. This would make communication much more effective and attractive. Moreover, a variety of electric aids, including wheelchairs and neural prostheses, would be controllable with a wide range of commands from the same interface. Therefore, this work describes a new sensor and method to facilitate tongue-activated commands.
It is the object of the invention to provide a method and a system for easing the communications capabilities of severely disabled persons and their control of their aids, where the costs of producing the system are low, thereby avoiding the drawbacks of the above mentioned prior art.